Beta-1,3-glucan is a polysaccharide, in which glucoses extend via beta-1,3-type bonds. Beta-1,3-glucan is synthesized by fungi, algae, higher plants, bacteria, etc.; its molecular weight broadly ranges from several thousands to several million. Research and development of this substance have advanced since it has been recognized to have anti-bacterial and anti-viral activities, blood-clotting activity, anti-cancer activity, immune-modulating activity, etc. The potency of the activity of beta-1,3-glucan is known to differ depending upon the structure and molecular weight thereof; beta-1,3-glucan extracted from fungi, etc., cannot exhibit the desired activity as is.
Consequently, research and development have been performed for the purpose of manufacturing beta-1,3-glucan or a laminarioligosaccharide having a suitable molecular weight. For example, regarding the latter, a method of manufacturing a laminarioligosaccharide (degree of polymerization of 2˜20) using an enzyme extracted from the cells of the genus Euglena is disclosed in Patent Document 1. A method of manufacturing a laminarioligosaccharide by reacting glucose with glucose-1-phosphate (G1P) using an enzyme extracted from the genus Bacillus is disclosed in Patent Document 2. A method of manufacturing a laminarioigosaccharide, which is characterized by reacting an Euglena algal body and/or Euglena algal body extract with a water-soluble beta-1,3-glucan, is disclosed in Patent Document 3.